This is an image I made for the wiki, as a colorful way to illustrate how many monsters there are per level. I didn't do this legitimately, but after thinking about it a bit, it isn't completely impossible to do. A goblin character with a Yendor prep and access to Glowing Guardian could probably do it.

So my challenge to us all is to go ahead and do it, and on as many maps as we can. Many maps have complicating factors such as subdungeon monsters and weird scripted events. I'll leave it up to the submitter to decide how to handle such things. The only hard and fast rules are

1) Every kill must match your level2) You must have at least one kill per level.3) Not a rule, but it is more impressive if you manage to kill everything.

There's venture cave. Important prep was GG, and finding wonnafyt helped wiht XP and exploration a lot. Careful with balanced dagger, don't pick it up too early. In case of no yendor, make good use of the randomly spawned drac altar such as I did here, but save it to for leveling up to 10. Impossible to do without humility pretty much so GG is autoprep.

Also, hitball subdungeon helped me here, as it always spawns enemies of the same level. If a subdungeon spawns enemies with a level higher then 1 or 2, make sure you kill them at appropriate times to help your XP gain.

Deffinitely practice it here before you try it somewhere else, it's tricky!

Also - I whish bandits and all the other humans had different... clothes or whatever. I know they all share the same boss trophy and all, but being able to tell them apart would be a nice thing since berserkers and bandits are simply not the same monster, and the hittball guys aren't any of those either.

Nicely done Lujo. My intuition says that this will be all but impossible for HARD and above, but I've seen some crazy things on this board. Maybe tomorrow Avatar will do it with a Purist Super Vicious Gaan Telet gnome priest.